Attention recently has been directed to implementing voice telephone services over the worldwide network commonly known as the Internet. WiFi calling is a new concept that allows cellular phones to operate a VoIP client to communicate with telephony switching equipment, thus allowing tolls to be bypassed. WiFi cellular telephones can automatically switch between conventional cellular and WiFi VoIP modes, even during the course of a conversation. With a WiFi cellular phone set, if a building has WiFi access, the call is handed off from the conventional cellular network to the WiFi LAN, taking advantage of VoIP technology to maintain the call without drop-out.
VoIP clients can be configured today with PBX extensions. Provided the destination extension is known, it can be dialed from the cell phone e.g. four digit extension dialing or PSTN breakout. Likewise, a device can receive calls if it is registered with the PBX, and the caller knows the extension number of the VoIP client. In these cases, tolls are also avoided. PBX extensions only have meaning within a PBX network. A drawback of this approach is that the VoIP client must be programmed as an extension on the PBX, and others must know the extension number in order to call the device.
VoIP clients can be reached by an IP address, the IP address having global scope, or internal scope defined by the network, which is similar to a PBX extension being valid only within the scope of the PBX. Today, VoIP clients can operate via a service provider, or point-to-point. Both models require a unique identifier, such as a number, to be mapped to an IP address. In the case of a service provider, the identifier is unique within the domain of the provider, a prerequisite so that communications can be routed through the service provider network. In the case of point-to-point protocols, the unique identifier is resolved directly by the calling device to obtain the destination IP address, and does not require a service provider to resolve the identifier and handle the routing.
Bridging a mobile to VoIP number can be accomplished via E.164 Number Mapping (ENUM) standard services, but requires that the carriers consult with the ENUM service. ENUM services have preference to WiFi over mobile, which is not cost beneficial to carriers and mobile operators. It also requires configuration, often static, to work correctly. A feature such as Force to PBX can also be used to force all calls to the cellular device via the PBX, but this often requires static configuration at the carrier, and does not provide a solution for toll bypass of calls originating from the cellular device.
Existing service providers, such as Skype® or Gizmo®, offer a new number, which then represents a VoIP application or subset of existing numbers. The application is provided by the service provider, and is used to register and access the service provider network. Calls are often limited to other members within the network or break out charges apply if the service provider must route the call via the public switched telephone network. The present application addresses the above-described issues encountered in WiFi calling by describing a model that allows a cellular device to make and receive calls over WiFi using its global number. This along with other related advantages are described herein.